I recently ran across a discussion of the Zeppelin bend (and its loop form), became intrigued, and did both more reading and some tying in rope and webbing. If what I've read is credible, the one source that called it "the best knot you've never heard of" may be right. It's very secure, like an 8, but doesn't jam and can easily be untied after loading (unlike an 8, water knot, or fisherman's). Supposedly, like an 8, it doesn't loosen when unloaded or when flogging as a bowline can. It doesn't capsize like an EDK, it doesn't creep when loaded cyclically like a water knot, it's symmetrical and easy to inspect for correctness like an 8 whether tied in rope or webbing. The one static loading test I found showed the Zepp loop superior to the rethreaded-8 in strength, but other than that I didn't find that anyone had done much lab testing on it.

There are lots of data and lots of debate (granted the heat:light ratio may be somewhat suboptimal) about the 8 vs bowline, fisherman's vs water knot, and EDK vs anything else, but searching here on Zeppelin gets mostly Led. Anyone use it, know why it's not used widely, have any test data on it?

I recently ran across a discussion of the Zeppelin bend (and its loop form), became intrigued, and did both more reading and some tying in rope and webbing. If what I've read is credible, the one source that called it "the best knot you've never heard of" may be right.

Although it's a real challenge to test it against all the other knots "you've never heard of!"

In reply to:

It's very secure, like an 8, but doesn't jam and can easily be untied after loading (unlike an 8, water knot, or fisherman's). Supposedly, like an 8, it doesn't loosen when unloaded or when flogging as a bowline can. It doesn't capsize like an EDK, it doesn't creep when loaded cyclically like a water knot,

Flogging testing is an undefined art --YMMV w/materials. But the zeppelin end-2-end knot does seem nicely resistant to loosening, at least in some mild conditions. I'm not sure I'd trust it to be so for rather unknown & out-of-sight uses (in contrast to the grapevine bend, e.g.). It has something to do with how the tails exit perpendicular to the axis of tension and with a right-angle turn, which makes them resistant to moving even in a relaxed state.

The offset water knot (EDK) can simply be made capsize-proof, for the usual use in abseiling (tie off the right tail with a stopper, or put an extra turn in the choking strand), and serves that purpose well, given its offset nature. The zeppelin offers nothing, here.

Creeping in the water-knot-in-tape is a mystery : some testing found it to occur in stiffer tapes but not new tubular, and then only at low loads (such as might come in abseil). There is a way to tie the water knot symmetrically so that each tail will finish on the interior side (testing found only the exterior tail of the known water knot to be slipping). Aric made one test of this just for break strength --not cyclical low-load slippage (which Moyer et al. did)-- and had that posted in The Lab, but it's gone, with him, now.

Of course, the common bowline should not be used without precaution against loosening, of which there are many ways. What the bowline offers is "PET"(ness) : "post-eye [formation] tying" --i.e., one can for the eye to whatever size, AND THEN tie the entire knot; there is no "first half" of the knot to tie and then re-thread, e.g.. (I've actually figured a variation of the zeppelin that does this, but it's a case of *theoretical* play bordering on comedy --could work, but hardly worth the bother.)

There is a chunkier version that TIB (tiable in-the bight (sans ends)) --essentially, implementing a different definition of "corresponding eye-knot". This would not be a fun knot to tie-in with, though.

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it's symmetrical and easy to inspect for correctness like an 8 whether tied in rope or webbing.

Whoa : it's not all so easily inspectable in tape --at least not in being a knot you've never heard of (or seen). It's not all so obvious what is going on in the crunched center of the knot. (And I think it's a dubious one for solid webbing rather than tubular.)

In reply to:

The one static loading test I found showed the Zepp loop superior to the rethreaded-8 in strength, but other than that I didn't find that anyone had done much lab testing on it.

There are lots of data and lots of debate (granted the heat:light ratio may be somewhat suboptimal) about the 8 vs bowline, fisherman's vs water knot, and EDK vs anything else,

And yet still when one looks at the test reports there are more unanswered points than information --such as exactly how the knot was tied (dressed & set). As you say, there's much noise in it.

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but searching here on Zeppelin gets mostly Led. Anyone use it, know why it's not used widely, have any test data on it?

I think we've both seen the one Treebuzz arborist's reporting, yes? --that was the stronger-than-fig.8-eyeknot case (w/o knowing how he dressed the latter). There was some other testing of A-vs-B sort, with cheap polypropylene laid ropes, in which the zeppelin came in among other interlocked-overhand-knots end-2-enders, weaker than the grapevine & fig.8 (and anchoring fig.8 eyeknots never broke (!)) --truck pulling specimen anchored to tree. Beyond that, I'm not recalling much of anything.

But, really, in rockclimbing, end-2-end knotting is pretty well defined: grapevine for semi-permanent sling formation in rope (and, by the evidence of testing, also in tape; less permanence seems wanted, here, though?!) ; the offset water knot (EDK) or a secured variation, for joining abseil lines --where being offset is the desired feature, and easy tying-- ; and ... what else? (A cordelette actually doesn't NEED any joining of ends : they can be brought out through the powerpoint knot and left untied!)

The zeppelin eyeknot (of the known form : tail of first half taken out to become eye and then brought back as joining end) might be worthwhile for tie-in; but there are many ways of tying in, some using known *technology* to bolster common knots.

OP - What do you want to use the knot for? There are plenty of other neat knots out there but in climbing they are just not as useful. For simply joining 2 ropes for rapelling, it's hard to beat the simple EDK.

I think the reality is that the EDK is just better. It pulls better, is easier to tie and inspect, and it's failure mode is incredibly easy to mitigate. There will be no surprises with the EDK because it has been widely used for ages.

If you start joining ropes like this when rapping I predict the following:

Your partner will think you're a sketchball.

Your partner will try to talk you out of rapping on ropes joined with that knot.

Your partner will insist you rap first.

Your partner will untie that knot and retie with an EDK or more common knot before they rap.

OP - What do you want to use the knot for? There are plenty of other neat knots out there but in climbing they are just not as useful. For simply joining 2 ropes for rapelling, it's hard to beat the simple EDK.

I forgot to add that I did use that knot once before but decided that didn't care for the big profile (compared to EDK) .

Why not just use a butterfly bend that every climber should know and not the zeppelin? It has the same basic structure and has all the benefits of the zeppelin with none of the obscurity.

Also, instead of an EDK, just use a flat double overhand (EDK wrapped twice). its as easy to tie as an edk, not much bigger than an edk, its stronger than an EDK, just as easy to inspect and doesn't slip like one.

Why not just use a butterfly bend that every climber should know and not the zeppelin? It has the same basic structure and has all the benefits of the zeppelin with none of the obscurity.

To put it another way, use known technology. But, as noted above (or, as opined above), ... why use either? (Btw, I think you'll fine the Z more slack-secure than the B .)

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Also, instead of an EDK, just use a[n offset dbl.overhand (EDK wrapped twice). its as easy to tie as an edk, not much bigger than an edk, its stronger than an EDK, just as easy to inspect and doesn't slip like one.

[nb: the knot isn't flat, but it is offset. :o]

Here's why : Occam's Razor, guided by an analysis of the needs for the end-2-end knot, cuts out the 2nd wrap of the yellow rope (as you present it in photos) --tucking that one out on the first pass, making an overhand in the yellow rope--; the 2nd wrap is made only in the red rope, which makes for a tighter choking at the knot's offset throat (i.e., it's nearly a closed circle --minimal helix). ("stronger than the EDK" isn't quite right : they are equally strong, in that both will hold abseil loading w/o issue.)

And, in (not uncommon) situations where the ropes are thick joined to thin, you would put the thin rope in the position of the red, and so the added knotting is done in the thinner line which saves bulk a bit. (Similarly with the EDK, which would "roll" only by the thinner line being forced out around the thicker, and for which such rolling can be precluded by tying an overhand stopper around with the thin tail around the thick, snug to the EDK .

ps: In your image of the finished knot --lower-right--, the red tail has moved out of best position (shown lower-left), going where the draw of the loaded mainlines want to rotate it anyway; it's best to set the knot against this, IMO.

Why not just use a butterfly bend that every climber should know and not the zeppelin? It has the same basic structure and has all the benefits of the zeppelin with none of the obscurity.

To put it another way, use known technology.

This was really the thrust of my original question. Known technology isn't always better technology, the organizational psychology literature is full of examples of how we tend to cling to the familiar even when superior alternatives are available. I was wondering if the obscurity of the Zeppelin bend is such an example, vs. yeah it's better but irrelevant because we already have good enough ones.

The Z and the B are very similar; ISTM that the only difference is that the Z is symmetrical. I don't know if that makes it more secure, or otherwise affects its performance, but it would be interesting to do some tests on it to see. Playing with both for a while, it does seem easier to inspect a Z and see immediately whether it's tied correctly.

I've tied Zs in various sizes of sling as well, and even though there's a "hidden" part inside, it's immediately obvious if it's not tied right. I haven't been able to find a way to mis-tie a Z in webbing that looks deceptively normal.

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Also, instead of an EDK, just use a[n offset dbl.overhand (EDK wrapped twice). its as easy to tie as an edk, not much bigger than an edk, its stronger than an EDK, just as easy to inspect and doesn't slip like one.

[nb: the knot isn't flat, but it is offset. :o]

I tried tying an offset double overhand, and it was easy to tie and inspect. It was pretty nearly as bulky as a Z or B though. The plain EDK was definitely smaller than any of the three. Still, though it is strong and small, the EDK's tendency to capsize (which if I understand correctly is where the pejorative "Euro death knot" comes from) seems to limit it to use as a temporary knot, like for one rappel. I wouldn't want to use it for anything I wanted to stay tied for any length of time. As a sailor I would never use it to join two lines to moor my boat for example.

(The only difference between having your rap knot fail and having your mooring knot fail is that in the former case you're beaten to death on the rocks vertically by gravity, while in the latter case you're beaten to death on the rocks horizontally by waves. Either way, secure knots are good!)